1. Field of the Invention
The present disclosure relates generally to microprocessors, and more specifically to methods for enhancing microprocessor performance and power through inductive voltage droop monitoring and correction.
2. Background Art
Microprocessor speed for a given design depends largely on supply voltage at the transistor level. Voltage regulators may be used to maintain a constant supply voltage to the microprocessor. The voltage provided externally by the regulator is higher than the voltage at the transistor level because it needs to compensate for the voltage drop on the package and microprocessor power supply rails. This voltage drop has two components: ohmic resistance (IR drop) and voltage droop (Ldi/dt).
Through proper package design, the IR voltage drop may be maintained below 10 mV. Voltage droops caused by inductive effects, on the other hand, are more difficult to manage and could cause a much larger voltage drop. A voltage droop refers to loss of supply voltage as a device tries to drive a load. For example, when power is supplied to a microprocessor, the sudden increase in current through the microprocessor causes a loss in the supply voltage due to the package inductance. In other words, the sudden increase in the current drawn by the microprocessor causes a voltage droop because there is a high rate of change of current through the microprocessor package inductance.
Depending on the power variation frequency, the microprocessor may hit the capacitance resonance frequency, in which case a large voltage droop (150 mV or more) can occur at the voltage supply at the transistor level. This can cause significant speed reduction and, in severe cases, microprocessor failure. Conventionally, operating margins were added in the timing analysis to compensate for voltage droops and ensure the microprocessor will function. As microprocessors and other semiconductor devices continue to become powerful and complex, preventing voltage droops to maintain a constant supply voltage has become an increasingly significant concern for developers.